This bad boy is Alpine's flagship unit and no matter what you think of Alpine it is way cool. I actually have to get the specs but as you can see it has a 3 disc in dash cd player and cassette...
This is Clarions flagship double din unit, it is a very good buy and I am currently considering one, it is considerably cheaper than the other double din units, has cd and cassette in dash and has lots of flashing lights...
Pioneer also has a radical flagship double din unit, which is awesome and comparable if not better than the alpine unit although only single cd. Pioneer head units are good value , look good and have a built in car alarm ( excellent idea ). This particular deck is also 40x4 watts and has 3 x rca outputs...
I have absolutely no experience with Rockford Fosgate head units but this one is one of their best, I know they make very loud speakers so I'm sure this is a good buy and is probably very cool wherever you are...
Sony 's head units are often overlooked as being cheap and not as good as many other more prestigious brands, but they do make very good value for money stereo's so if you have a limited budget sony probably is a reasonable compromise although they are a bit behind the times in relation to new technology...
If you can live with the boring look of their stuff blaupunkt are a good quality brand from people who know their stuff. Blaupunkt do many of the stereo's for car manufacturers, probably not the brand if you are looking for a stand out system, they also invented the key card for security an excellent idea if the bad guys see it before they break your window...